Living in center city Philadelphia, I can confidently say there are a couple unintended reasons these things may require less emptying: First, they're often so dirty that no one would want to grab the handle and open the door to throw trash in (I avoid them at all costs myself). Who wants to touch a trashcan even when it's clean? Second, if you're willing to grab the trash-encrusted handle and open the door, they're frequently jammed (or locked?) shut. On the few occasions where I was forced to use them because there were no other trashcans in sight, they were difficult or impossible to open.
So what do people do? They throw their trash on the ground, or they find a nearby trashcan that doesn't require contact to use. It's not unusual to see bags of trash sitting by these things with random garbage scattered around or on top of them.
I lived at 3rd and South for a while both before and after these were deployed. The old cans were emptied once or twice a day by sanitation workers. Very often, those sanitation workers would also pick up trash off the street around the cans. When the Big Belly's were installed, they started coming around every other day or so instead. No one touches these things. People simply throw their trash at them and walk away. I once saw a Big Belly covered by a pile of trash near 5th and South.
I got really good at opening them with the heal of my shoe, or using a napkin. Very often, though, they were either jammed shut or stuffed full.
The city probably could have just stopped collecting trash altogether to achieve the same result and save even more money.
The primary issue with these is that they have a user interface that increases the friction and time of throwing things away. Having to walk up and grab the handle (which is usually disgusting), throw in your garbage, and then close it, adds a small, though significant enough amount of time that most people can't be bothered to do it (many Philadelphians just throw garbage on the street). Additionally, it is difficult to throw away larger amounts of trash or loads that would require two hands to dispose of.
Is the city center doing well, or decaying? I know some cities have vibrant cores but decaying inner peripheries. (i.e. between downtown and newer suburbs)
The big reason I wanted to visit was the history, and also (this might seem silly) because Bill Cosby is from there.
It's also notable that they stopped doing those events at all because booing of new comedians was a general problem everywhere.
Philly does have a lot of problems, but it annoys me that we have a reputation as particularly bad crowds at sporting events etc based on a few notable incidents. If you look at basically any other city where large crowds of drunk obnoxious people congregate they have similar incidents.
Philly really isn't that bad... though I suspect many HNers who are used to the shinier west coast cities would experience a bit of culture shock.
I feel your pain, though, about just trying to find a bin - I'll walk blocks without finding one in some parts of the city.